Nuclear Reactor Core Modeling with Restricted Eigensystem Conditioning
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Solution Overview
Problem
Current methods for modeling nuclear reactor cores face challenges in achieving accurate and efficient neutron flux calculations due to slow convergence and high computational efforts, particularly with Coarse Mesh Rebalancing procedures that depend on the proximity of the coarse mesh level to the full-core diffusion level.
Innovation Solution
A computer-implemented method that partitions the reactor core into cubes for grid-based calculations, using an iterative solving procedure to condition the eigensystem into a restricted eigensystem for selected neutron energy groups, and employing a multi-level V-cycle approach to improve convergence accuracy and computational efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Coarse Mesh Rebalancing procedures are used to accelerate eigensystem solving, then computational efficiency is improved, but convergence accuracy deteriorates and may lead to convergence stagnation
Solution Approach 1:
The patent segments the neutron energy spectrum into multiple discrete energy groups. Instead of treating the continuous energy spectrum as a single entity, the method divides it into G energy groups with group boundaries E_g. This segmentation allows the eigensystem to be solved for each energy group separately, improving both convergence accuracy and computational efficiency by reducing the coupling between energy groups while maintaining spectral resolution.
Solution Approach 2:
The patent changes the parameter representation by introducing discrete energy group indices (g, g') and group boundary energies (E_g) to transform the continuous energy spectrum problem into a discrete multi-group problem. This parameter transformation enables the use of iterative solving procedures that converge more reliably while maintaining accuracy, as each energy group can be treated with optimized numerical parameters.
2Adaptability or versatility
If iterative solving procedures are used for the eigensystem, then flexibility in handling complex core geometries is improved, but computational time increases
Solution Approach 1:
The patent segments both the spatial domain (core divided into cubes/nodes) and the energy domain (divided into G energy groups). This dual segmentation transforms the complex continuous problem into a discrete multi-group multi-node system that can be solved iteratively with reduced computational burden per iteration, while maintaining the ability to handle arbitrary core geometries and configurations.
Solution Approach 2:
The patent applies partial action by solving the eigensystem iteratively for each energy group separately rather than solving the full continuous energy problem in one step. This partial approach to energy group treatment reduces the computational complexity of each iteration while still capturing the essential physics across the full energy spectrum, thereby reducing total computational time.
Data Source
AI summary
A computer implemented method for modelizing a nuclear reactor core, including the steps of: partitioning the core in cubes to constitute nodes of a grid for computer implemented calculation, calculating neutron flux by using an iterative solving procedure of at least one eigensystem, the components of an iterant of the eigensystem corresponding either to a neutron flux, to a neutron outcurrent or to a neutron incurrent, for a respective cube to be calculated.The neutrons are sorted in a plurality of neutron energy groups, and the eigensystem iterative solving procedure includes a substep of conditioning the eigensystem into a restricted eigensystem corresponding to the eigensystem for a selection of some neutron energy groups.